Quantum dot systems are studied theoretically from the point of view of realization of quantum bit using the orbital state of electronic motion in a quantum dot. Attention is paid to several effects which can influence significantly the application of quantum dot electronic orbital states in quantum computing, for example, the effect of upconversion of the population and the incomplete depopulation of electronic orbital states, the effect of optical line broadening and presence of continuous background in optical spectra. Attention is also paid to the effect of upconversion of electronic population to the wetting-layer or above-barrier electronic states in quantum dot samples. Interaction of electrons with the longitudinal optical phonons is shown to play a significant role in these effects. Possible impact of these phenomena on the realization of quantum bit based on electronic orbital states in quantum dots is discussed.

Wetting layer

10.1109/tnano.2003.820814

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Citations (17)

Relaxation of electron energy in polar semiconductor double quantum dot

Physica E Low-dimensional Systems and Nanostructures (2002)

K. Král Z. Khás P. Zdeněk M. Čerňanský C.Y. Lin

10.1016/s1386-9477(01)00467-2

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Citations (1)

Study of luminescence kinetics of AlN:Mn4+ under volume. Photo-excitation and surface excitation in plasma discharge

physica status solidi (a) (1980)

J. Pastrňák J. Oswald F. Karel Z. Khás

The study of the luminescence decay curves of the 2.07 eV emission band of AlN:Mn4+ under different excitation conditions gives for the life time of the excited state of Mn4+ centres the value τ = 1.18 ms. The influence of shallow traps on the luminescence kinetics for the excitation via oxygen impurity centres is also demonstrated. The kinetics under the excitation with the help of discharge plasma is governed by the presence of a nonluminescent surface layer, which influences the energy transport of excitation energy from the surface to the luminescence centres of the volume. The thickness of the layer changes with the exploitation time. A model for the radical recombination luminescence based on the resonant energy transfer between oxygen donor levels in AlN is suggested. [Russian Text Ignored.]

10.1002/pssa.2210620140

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Citations (4)

Electron-LO-Phonon Quantum Kinetics in quantum Dots

Journal de Physique I (1997)

K. Král Z. Khás

Quantum kinetic equations are solved numerically for the process of the relaxation of an excited electronic system in a cubic quantum dot in a GaAs/AL x Ga 1-x As structure with the electron-LO-phonon interaction included and with the carrier-carrier interaction neglected. The theory is developed within the equation of motion method for the reduced density matrices. It is shown that near the low electron and hole density limit a relatively broad interval of the dot lateral size may exist in which the relaxation of the electrons may develop at a picosecond time scale.

10.1051/jp1:1997139

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Incomplete electronic relaxation and population upconversion in quantum dots

arXiv (Cornell University) (2003)

K. Král Z. Khás P. Zdeněk

We calculate the electronic relaxation of a single electron in a quantum dot with two electronic orbital states, and with the electronic coupling to the longitudinal optical modes of the lattice vibrations included in the multiple scattering approximation to the electronic self-energy. This model shows that there is an incomplete electronic relaxation from the excited state to the ground state and also the incomplete increase of the population of the excited state after resonantly exciting the ground state. These theoretical results are compared with very similar recent findings reported in experimental papers.

Photon Upconversion

10.48550/arxiv.cond-mat/0304699

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